Hydrogel materials are useful in coating, sealing and adhesion of soft tissues, for example as described in U.S. Pat. No. 5,410,016 to Hubbell et al., U.S. Pat. No. 5,800,373 to Melanson et al., and U.S. Pat. Nos. 5,844,016, and 5,900,245 to Sawhney et al. Important properties of these hydrogels are their biocompatibility, their ability to adhere strongly to tissue, and good mechanical compliance, which is appropriately matched to that of the tissue. Biocompatibility is achieved by the use of materials that are especially compatible with tissue, such as polyalkylene oxides, and by a high water content, similar to that of the tissue being coated.
However, these gels are less useful in situations in which the gels are subject to high mechanical stress. An example of such a situation is in the repair of bone and other skeletally-related tissues, such as cartilage, the tibial meniscus, tendons and ligaments, spinal disks, and muscle (collectively, “orthopedic tissues”), or in composite implants intended for such uses. Repair of injuries, disease or defects of orthopedic tissues can be difficult because the gel needs to offer protection to the structures under mechanical stress. Tight adherence to the substrate is often beneficial in achieving this purpose. Repair of articular cartilage is especially difficult. A surface must be provided which is resistant to abrasion and provides cushioning during regeneration and maturation of the cartilage, for example, following implants of tissues, cells or aggregates. On the other hand, appropriate stress transmitted to the cells facilitates appropriate alignment and generation of a normal intercellular matrix. Similar considerations apply to bone regeneration, especially at joints.
Traditional hydrogels are not strong enough to withstand the applied stresses, particularly over the length of time required, especially for long periods of time such as those required for regeneration of bone or connective tissue. Such gels also tend to swell extensively in aqueous environments, which can interfere with mechanical properties of the injured joint or other site. Moreover, hydrogels do not tend to adhere strongly to tissue, especially to moist tissue, or when pre-formed before application to tissue. On the other hand, traditional solid implants (which typically are formed of hydrophobic materials) can be too rigid and brittle, thereby impeding or preventing tissue repair or regeneration. They may also lack lubricity, which can compromise performance in joints, as well as pose a risk of abrasion of the opposing surface.
A material that has the appropriate balance of strength and compliance as well as the biocompatibility of a hydrogel, and that has strong adherence to orthopedic tissues, is needed.
It is an object of the present invention to provide biocompatible hydrogels which strongly adhere to orthopedic tissues.
It is another object of the present invention to provide hydrogels with strong mechanical properties.
It is another object of the present invention to provide monomers from which hydrogels with strong mechanical properties can be formed, and methods of use thereof.